Various wireless access technologies have been proposed or implemented to enable mobile stations to perform communications with other mobile stations or with wired terminals coupled to wired networks. Examples of wireless access technologies include GSM (Global System for Mobile communications) and UMTS (Universal Mobile Telecommunications System) technologies, defined by the Third Generation Partnership Project (3GPP); and CDMA 2000 (Code Division Multiple Access 2000) technologies, defined by 3GPP2.
As part of the continuing evolution of wireless access technologies to improve spectral efficiency, to improve services, to lower costs, and so forth, new standards have been proposed. One such new standard is the Long Term Evolution (LTE) (also referred to as EUTRA (Evolved Universal Terrestrial Radio Access)) standard from 3GPP, which seeks to enhance the UMTS technology.
An issue associated with uplink wireless transmissions is power consumption associated with processing of information to be transmitted on the uplink. It is desired to achieve a low peak-to-average-power ratio (PAPR) to improve power efficient performance. However, in some implementations, achieving the desired power efficient performance may require use of relatively expensive power amplifiers in transmitters of mobile stations due to large power amplifier backoff requirements. Power amplifier backoff refers to operating the power amplifier at an output power level that is lower than the peak power level. A large power amplifier backoff (lower average power level relative to the peak power level) reduces the efficiency of the power amplifier.
Other goals associated with wireless transmission is wider bandwidth, higher spectral efficiency, and higher-order MIMO (multiple input, multiple output). MIMO refers to wireless transmission in which the transmitter has multiple antennas and the receiver has multiple antennas, where multiple input means multiple transmitted signals into the channel, whereas multiple output means multiple signals at the output of the channel. Conventional wireless transmitters may not provide desired characteristics in an efficient manner.